Epithelial surfaces of the upper gastrointestinal tract of the blue-tongues lizard, Tiliqua scincoides: a scanning electron microscope study

Abstract

The surface epithelium of the oesophagus, stomach and small intestine of healty T. scincoides was examined by scanning electron microscopy and the findings confirmed by both light and transmission microscopy. The oesophagus was lined by ciliated, goblet and microvillous cells. Its topography appeared similar to the trachea and major bronchi of a number of mammals and birds. Throughout the length of the stomach microvillous cells were uniformly arranged on the gastric rugae. The cells were slightly convex and sparsely populated by microvilli, which appeared more numerous at intercellular margins. Swollen epithelial cells, approximately twice the size of the adjacent cells, were scattered throughout the gastric epithelium. Cells with focal apical erosions were found in isolated regions, being relatively more numerous in the distal stomach. The openings of the gastric glands were observed as invaginations of the epithelial surface and were most prominent near the tops of the gastric rugae. The small intestine was lined by epithelial cells covered by long, densely packed microvilli. Goblet cells were interspersed along the surface of the intestinal villi. Except for the oesophagus, the topography of the upper gastrointestinal tract of T. scincoides closely resembles that of homologous regions of the mammalian gut.